Phthalides and naphthalides

ABSTRACT

THIS INVENTION RELATES TO 1-NAPHTHOL PHTHALEIN INDICATOR DYES INCLUDING PHTHALIDES AND NAPHTALIDES WHEREIN ONE OF THE P-HYDROXYNAPHTHYL RADICALS IS SUBSTITUTED WITH A HYDROGEN-BONDING GROUP ON A CARBON ATOM ADJACENT TO THE CARBON ATOM CONTAINING THE NAPHTHOLIC -OH. IN A PREFERRED EMBODIMENT, BOTH OF THE P-HYDROXYNAPHTHYL RADICALS SUBSTITUTED WITH HYDROGEN-BONDING GROUPS. THESE INDICATOR DYES, ESPECIALLY THOSE OF THE PREFERRED EMBODIMENT, PROCESS A RELATIVELY HIGH PKA.

United States Patent 3,833,614 PI-ITHALIDES AND NAPHTHALIDES Myron S. Simon, West Newton, Mass., assignor to Polaroid Corporation, Cambridge, Mass. No Drawing. Filed Jan. 4, 1971, Ser. No. 103,865 Int. Cl. C0711 7/20 U.S. Cl. 260-343.2 R x 22 Claims ABSTRACT OF THE DISCLGSURE This invention relates to l-naphthol phthalein indicator dyes including phthalides and naphthalides wherein one of the p-hydroxynaphthyl radicals is substituted with a hydrogen-bonding group on a carbon atom adjacent to the carbon atom containing the naphtholic OH. In a preferred embodiment, both of the p-hydroxynaphthyl radicals are substituted with hydrogen-bonding groups. These indicator dyes, especially those of the preferred embodiment, possess a relatively high pKa.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to novel chemical compounds, and more specifically, it relates to a new class of naphthol phthalein indicator dyes. in a particular aspect it relates to l-naphthol phthaleins useful as optical filter agents in photographic processes for protecting an exposed photosensitive material from post-exposure fogging during development in the presence of extraneous incident light.

2. Description of the Prior Art A number of photographic processes by which images may be developed and viewed within seconds or minutes after exposure have been proposed. Such processes generally employ a processing composition which is suitably distributed between two sheet-like elements, the desired image being carried by one of said sheet-like elements. The resulting images may be in black-and-white, e.g., in silver, or in one or more colors. Processing may be conducted in or outside of a camera. The most useful of such processes are the diffusion transfer processes which have been proposed for forming silver or dye images, and several of these processes have been commercialized. Such processes have in common the feature that the final image is a function of the formation of an image-wise distribution of an image-providing reagent and the diffusion transfer of said distribution to or from the stratum carrying the final image, whether positive or negative.

U.S. Pat. No. 3,415,644 discloses a composite photosensitive structure, particularly adapted for use in reflection type photographic diffusion transfer color processes. This structure comprises a plurality of essential layers including, in sequence, a dimensionally stable opaque layer; one or more silver halide emulsion layers having associated therewith dye image-providing material which is soluble and diffusible, in alkali, at a first pH, as a function of the point-to-point degree of its associated silver halide emulsions exposure to incident actinic radiation; a polymeric layer adapted to receive solubilized dye image-providing material diffusing thereto; a polymeric layer containing sufficient acidifying capacity to effect reduction of a processing composition from the first pH to a second pH at which the dye image-providing material is substantially nonditfusible; and a dimensionally stable transparent layer. This structure may be exposed to incident actinic radiation and processed by interposing, intermediate the silver halide emulsion layer and the reception layer, an alkaline processing composition providing the first pH and containing a light-reflecting agent,

for example, titanium dioxide to provide a white background. The light reflecting agent (referred to in said patent as an opacifying agent) also performs an opacifying function, i.e., it is effective to mask the developed silver halide emulsions and also acts to protect the photoexposed emulsions from postexposure fogging by light passing through the transparent layer it the photoexposed film unit is removed from the camera before image formation is complete.

In a preferred embodiment, the composite photosensitive structure includes a rupturable container, retaining the alkaline processing composition having the first pH and light-reflecting agent, fixedly positioned extending transverse a leading edge of the composite structure in order to effect, upon application of compressive pressure to the container, discharge of the processing composition intermediate the opposed surfaces of the reception layer and the next adjacent silver halide emulsion.

The liquid processing composition distributed intermediate the reception layer and the silver halide emulsion, permeates the silver halide emulsion layers of the composite photosensitive structure to initiate development of the latent images contained therein resultant from photoexposure. As a consequence of the development of the latent images, dye image-providing material associated with each of the respective silver halide emulsion layers is individually immobilized as a function of the point-topoint degree of the respective silver halide emulsion layer photoexposure, resulting in imagewise distributions of mobile dye image-providing materials adapted to transfer, by diflusion, to the reception layer to provide the desired transfer dye image. Subsequent to substantial dye image formation in the reception layer, a sutficient portion of the ions of the alkaline processing composition transfers, by diffusion, to the polymeric neutralizing layer to effect reduction in the alkalinity of the composite film unit to the second pH at which dye image-providing material is substantially nondiffusible, and further dye image-providing material transfer is thereby substantially obviated.

The transfer dye image is viewed, as a reflection image, through the dimensionally stable transparent layer against the background provided by the reflecting agent, distributed as a component of the processing composition, mtermediate the reception layer and next adjacent silver halide emulsion layer. The thus-formed stratum effectively mas ks residual dye image-providing material retained in association with the developed silver halide emulsion layer subsequent to processing.

In the copending U.S. Patent Application Ser. No. 786,- 352 of Edwin H. Land, filed Dec. 23, 1968, now abandoned, and U.S. Patent Application Ser. No. 101,968 filed Dec. 28, 1970, now U.S. Pat. No. 3,647,437 in part a continuation of Ser. No. 786,352, an organic light-absorbing reagent (or optical filter agent), such as a dye, which is present as a light-absorbing species at the first pH and which may be converted to a substantially non-light-absorbing species at the second pH is used in conjunction with the light-reflecting agent to protect the selectively exposed silver halide emulsions from post-exposure fogging when development of the photoexposed emulsions is conducted in the presence of extraneous incident actinic radiation impinging on the transparent layer of the film unit.

In copending U.S. Patent Application Ser. No. 103,392 of Myron S. Simon and David P. Waller filed J an. 4, 1971, now U.S. Pat. No. 3,702,245, pH-sensitive dyes derived from certain hydroxy-substituted carbocyclic aryl compounds, viz., particular phenols and naphthols are disclosed as useful as optical filter agents for absorbing incident radiation actinic to selectively exposed photosensitive materials within a predetermined wavelength range in the longer wavelength region of the visible spectrum. Certain of the novel dyes disclosed therein comprlse the subject matter of the present invention, namely, phthaleins containing two naphthol radicals at least one of which s substituted with a hydrogen-bonding group. These indicator dyes find utility as optical filter agents in photographic processes employing alkaline processing solutions.

SUMMARY OF THE INVENTION It is the primary object of the present invention to provide novel phthalein indicator dyes derived from l-naphthols.

It is a further object of the present invention to provide naphthol phthalein indicator dyes useful as optical filter agents in photographic processes for preventing postexposure fogging of a selectively exposed photosensitive material during development in the presence of incident li ht.

Other objects of this invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the processes involving the several steps and the relation and order of one or more of such steps with respect to each of the others, and the products and compositions possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

According to the present invention, there is provided a novel class of phthalein indicator dyes derived from 1- naphthols which contain a p-hydroxynaphthyl radical possessing a hydrogen-bonding group substituted group substituted on a carbon atom adjacent to the p-hydroxy group, a second p-hydroxynaphthyl radical and a ringclosing moiety selected from a phthalide and naphthalide, which indicator dyes will be defined with greater particularity hereinafter.

The indicator dyes f the present invention, like phthalein indicators in general such as phenol phthalein and l-naphtholphthalein, possess spectral absorption characteristics which are reversibly alterable in response to changes in environmental pH. These dyes possess a highly colored form capable of absorbing visible radiation in alkaline media at a first pH value above their respective pKa and a substantially colorless form, i.e., a form which is substantially non-light-absorbing in the visible spectrum in less alkaline media at a second pH value below their respective pKa. By pKa is meant the pH at which about 50% of the dye is present in its light-absorbing form and about 50% is present in its non-light-absorbing form.

It will be appreciated that such compounds will find utility in titrations and other analytical procedures where phthalein indicator dyes are commonly employed, for example, to measure changes in pH value as reflected by the change in color of the dye from one color to another or from colored to colorless or vice versa. The indicator dyes of the present invention, however, compared to conventional naphthol phthaleins possess a higher pKa which render them useful as optical filter agents in photographic processes performed under alkaline conditions, and certain of the indicator dyes provided herein are useful in photographic processes employing highly alkaline media.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description.

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, it has been found that the pKa of l-naphthol phthaleins, i.e., the pKa that generates color, may be increased by substituting one of the p-hydroxynaphthyl radicals with a hydrogen-bonding group on a carbon atom adjacent to the para hydroxy wherein one of R and R is a hydrogen-bonding group having a negative charge in basic solution and the other is hydrogen; B is a p-hydroxynaphthyl radical; and X represents the atoms necessary to complete a ring-closing moiety selected from a phthalide and a naphthalide. Preferably, R is a hydrogen-bonding group and R is hydrogen.

In the above formula, any hydrogen-bonding group may be used that is capable of raising the pKa. The association of two atoms through hydrogen to form a hydrogen bond between or within molecules is well known. When hydrogen is attached to an electronegative atom, for example, 0 or N, the resultant bond is polarized. If directed toward another atom (M) with an unshared pair of electrons, the hydrogen acts as a bridge between the atoms (O-H M due to the electrostatic attraction to both atoms between which the hydrogen proton can be transferred. In the present invention an intramolecular hydrogen bond is formed between the p-hydroxy group and an adjacent hydrogenbonding group, i.e., a group containing a heteroatom possessing an active unshared pair of electrons, such as, O, N, S or halogen, e.g., R, which has a free electron pair or a negative charge in basic solution and which is capable of forming a 5-, 6- or 7-membered and preferably a 5- or 6-membered hydrogen-bonded ring with the p-hydroxy group. Preferably, the heteroatom in the hydrogenbonding group has attached to it a proton which is more acidic than the proton on the naphtholic OH and ionizes in basic solution to a negative charge. Such groups include, for example, carboxy; hydroxy; o-hydroxyphenyl; bis trifluoromethyl carbinol; sulfonamido (NH-SOz-R wherein R may be alkyl, aryl, alkaryl); and sulfamoyl (SO NHR wherein R may be alkyl, aryl, alkaryl). Suitable R and R substituents include branched or straight chain alkyl, e.g., methyl, ethyl, isopropyl, n-butyl, t-butyl, hexyl, octyl, dodecyl, hexadecyl, octadecyl and eicosanyl; aryl, e.g., phenyl and naphthyl; and alkaryl, e.g., benzyl, phenethyl, phenylhexyl, p-octylphenyl and p-dodecylphenyl.

Where it is desired that the indicator dye be substantially immobile or non-diifusible in the processing solution, compounds containing a sulfamoyl or sulfonamido substituent afford the distinct advantage of allowing the immobilizing function to be combined with the hydrogen bonding function by selecting sulfonamido or sulfamoyl (SO -NHR') groups containing as R or R an immobilizing group, such as, hexadecyl or p-dodecylphenyl.

The compounds represented in the above formula may contain substituents other than those specified. Besides the hydrogen-bonding groups, the naphthyl radicals may contain additional substituents and likewise, the ring-closing moiety may contain other substituents as may be desired.

In the preferred embodiment of the present invention R is hydrogen, R is a hydrogen-bonding group, and the second p-hydroxynaphthyl radical also is substituted with a hydrogen-bonding group.

wherein R and R the same or dilferent, each are hydrogen-bonding groups having a negative charge in basic solution and X has the same meaning as in Formula (I) above.

Though the pKa of l-naphthol phthaleins including both phthalides and naphthalides may be increased by substituting only one of the p-hydroxy-naphthyl radicals with a hydrogen-bonding group in the 2- or 8-position, a further increase in pKa may be achieved by substituting both p-hydroxynaphthyl radicals with a hydrogen-bonding group. This elfect is especially apparent when the group is substituted in the 2-position. Preferred hydrogen-bonding groups capable of ionizing in base to a negative charge are carboxy, sulfonamido and sulfamoyl.

As noted above, the indicator dyes are represented in the above formulae may contain additional substituents as may be desired which do not interfere with the function of the dye for its selected ultimate use. Typical substituents include branched or straight chain alkyl, such as methyl, ethyl, isopropyl, t-butyl, octyl, hexadecyl, and eicosanyl; aryl, such as, phenyl and naphthyl; alkaryl, such as, benzyl, phenethyl, phenylhexyl, and p-dodecylphenyl; alkoXy, such as, methoxy, ethoxy, butoxy, l-ethoxy-Z-(fi-ethoxyethoxy) and octadecyloxy; aryloxy, such as phenoxy, benzyloxy and naphthoxy; alkoxyalkyl, such as methoxyethyl, ethoxyethoxyethyl and dodecyloxyethyl; halo, such as, fluoro, bromo and chloro; sulfo; carboxy; hydroxy; and amino includng monoand disubstituted amino, e.g., N-alkylamino and N,N-dialkylamino. Such substituents may be substituted on the first and/or second naphthyl radical and/or ring-closing moiety.

Specific examples of naphthol indicator dyes within the scope of the present invention are as follows:

OH OH OH OH Various methods may be employed in preparing the indicator dyes described above. Phthalein dyes including phthalides and naphthalides may be prepared by reacting the appropriate anhydride, acid or acid chloride, e.g., phthalic or naphthalic anhydride with the selected naphthol at elevated temperatures usually in the presence of a suitable catalyst, such as a Lewis acid catalyst.

Another method of preparing these phthaleins comprises reacting the selected naphthol with phthalaldehydic or naphthalaldehydic acid in the presence of a mild acid catalyst, e.g. toluene p-sulfonic acid, to yield the corresponding (n)phthalidyl-substituted intermediate which is oxidized by treating with, for example, dichlorodicyanoquinone. The oxidized intermediate is then reacted with another aromatic compound which may be a naphthol in the presence of an acid catalyst to yield the desired dye. Using this method both symmetrical and unsymmetrical indicators may be prepared by selecting respectively, as the second aromatic compound, a naphthol that is the same or that is different from the starting naphthol initially reacted with aldehydic acid. This method of preparing l-naphthol phthaleins and phthaleins derived from other selected aromatic compounds forms the subject matter of copending U.S. Patent Application Ser. No. 108,662 of Alan L. Borror filed Jan. 21, 1971.

Naphthol phthaleins also may be prepared by forming a (na)phthalidyl-substituted intermediate which is reacted in aqueous alkali with a naphthol, the same or difierent from the starting naphthol to form the leuco dye which is then oxidized to yield the indicator. This method forms the subject matter of copending U.S. Patent Application Ser. No. 202,615 of Eva R. Karger and Paul T. MacGregor filed Nov. 26, 1971. Another method of preparing naphthol phthaleins comprises the silver-catalyzed reaction of a 3-halo-3-(naphthyl) naphthalide-1,8 intermediate with a naphthol, the same or difi'erent from that comprising the 3-naphthyl substituent of the intermediate. This method forms the subject matter of copending U.S. Patent Application Ser. No. 192,638 of Richard B. GreenWald filed Oct. 26, 1971, now U.S. Pat. No. 3,702,245. The preparation of Z-carboxy-l-naphthols by treating a naphthalene diol with carbon dioxide and an alkali metal alkoxide or by acetylation of a naphthalene diol followed by converting the acetyl to a free acid group form the subject matter of copending U.S. Patent Applications Ser. Nos. 174,170 and 174,171, respectively, of Richard B. Greenwald both filed Aug. 23, 1971, now abandoned.

The following Examples are given to further illustrate the present invention and are not intended to limit the scope thereof.

EXAMPLE 1 Preparation of the compound of formula (7) (a) Dry 1-hydroxy-2-naphthoic acid (50 gms., 0.266 mole) was suspended in 350 ml. dry benzene in a flamedried 1 liter l-neck round bottom flask under an air condenser and drying tube. Thionyl chloride (31.7 gms., 0.266 mole) was added in one portion followed by 1.5 ml. dry N,N- dimethyl-formamide. The reaction mixture was stirred magnetically 2-3 days at room temperature. Insoluble material (6.5 gms.) was removed by filtration, and the yellow-tan filtrate was evaporated to dryness to give pale yellow l-hydroxy-Z-naphthoyl chloride, m.p. 8788 C. Chilled anhydrous methanol ml.) was added quickly to the solid chloride in an exothermic reaction. The partial solution was heated about 5 minutes on the steam bath under a drying tube then allowed to cool. The suspension was chilled and the solid was collected to give 43 gms.

(92% by weight) l-hydroxy-Z-methyl naphthoate.

(b) l-Hydroxy-Z-methyl naphthoate (30.2 gms., 0.149 mole) was dissolved in 400 ml. of dry l,l,2,2-tetrachloroethane in an Erlenmeyer flask fitted with a drying tube. The solution was chilled in an ice bath, and anhydrous aluminum chloride (84 gms., 0.625 mole) was added cautiously in portions. After about one-third of the catalyst was added, vigorous hydrogen chloride evolution ceased so that subsequent addition could be made more rapidly. Nitrobenzene (100 ml.) was added to the chilled dark green suspension, and the mixture was swirled intermittently until a rich brown solution resulted. The complex solution was allowed to stand for about /2 hour before use.

3,3-Dichloronaphthalide (37.8 gms., 0.149 mole) was dissolved in 100 ml. of l,1,2,2-tetrachloroethane in a flame-dried 2 liter 3-neck round bottom flask fitted With an addition funnel, air condenser, mechanical stirrer and drying tube. The solution was chilled in an ice bath; the previously prepared complex solution was decanted into the addition funnel and added dropwise over 30-60 minutes to the well-stirred reaction mixture. A rich purple color developed immediately. The reaction mixture was stirred and allowed to come to room temperature overnight.

Excess ice (300-500 gms.) was added cautiously to the almost solid reaction mixture followed by 20 ml. concentrated hydrochloric acid; the addition funnel and condenser were replaced by a Claisen distillation head, and the organic solvents were distilled with steam. The crude product separated as a yellow-brown solid from the hot dilute acid; it was collected directly, and air dried overnight.

Drying was completed in a vacuum oven, and the dried solid was taken up in hot glacial acetic acid (about 1 g./ 10 ml.) and insoluble material was removed by filtration; the ketol crystallized on standing and was collected and dried. Trace impurities were removed by solution in hot toluene (about 1 g./5 ml.) from which any insoluble material was separated. Recovery of 3-hydroxy-3-(3- carbomethoxy-4'-hydroxynaphthyl) naphthalide-1,8 was about 50-60% by Weight.

(c) A solution of 1 equivalent of the naphthalide obtained in step (b) and 3 equivalents of l-naphthol was prepared in dry acetic acid (about 1 gm./l5- ml.). Boron trifluoride etherate (1 equivalent) was added, and the reaction mixture was heated to reflux for several hours. The

11 solid which precipitated was collected and washed with ether and then hydrolyzed with hot methanolic sodium hydroxide to yield the title compound (melting range 277-279 C.).

EXAMPLE 2 Preparation of the compound of formula (17) (a) A mixture of 3.6 gms. of diisopropylethylamine and 3.6 gms. of n-propylamine was added dropwise to 7.3- gms. of 1-carbomethoxynaphthalene-Z-sulfonyl chloride in 25 ml. of chloroform while maintaining the temperature between 50 and 60 C. The resulting solution was kept at 50-60 C. for 15 minutes at which time a precipitate began to form. Heating was continued for an additional 30 minutes. The solution was then cooled, acidified with 10% hydrochloric acid and the chloroform evaporated. Three recrystallizations of the residue from benzene-hexane yielded about 4.5 gms. of 2-n-propylsulfamoyl-l-naphthol (melting range 61-64 C.).

(b) A mixture of 2.4 gms. of the sulfamoyl intermediate prepared in step (a) above and 1.8 gms. of naphthalaldehydric acid were dissolved in 30 ml. of acetic acid and 30 ml. of 12% p-toluene sulfonic acid in acetic acid was added. The resulting solution Was heated at reflux overnight. The reaction mixture was poured into an equal volume of cold water. The precipitate formed was collected and recrystallized from a benzene-petroleum ether mixture to yield 3.0 gms. of solid (melting range 189 191 C.).

(c) A solution of 50 ml. of aqueous 10% sodium hydroxide was flushed with nitrogen for 2 hours. To the solution was added 2.3 gms. of the product of step (b) and 1.4 gms. of 2-n-propyl-sulfamoyl-l-naphthol as prepared in step (a). The resulting solution was heated at 60 C. overnight. The temperature was raised to 70 C. and heating was continued for about 48 hours. The reaction mixture was then cooled and the pH adjusted to approximately 1.0 with dilute hydrochloric acid. The white solids formed were collected and washed and taken up in benzene. The benzene solution was treated with charcoal, filtered and concentrated until solids began to precipitate. The precipitate was collected yielding 2.5 gms. of White solid (melting range 178-l80 C. dec.).

(d) 710 mgs. of the product of step (c) were dissolved in about 30 ml. of dimethylformamide. To this was added 230 mgs. of 57% sodium hydride. The resulting solution was heated at 80 C. until the evolution of hydrogen had ceased. Then 470 mgs. of silver oxide was added, and the mixture was stirred overnight at room temperature. Heating was continued at 80 C. for 8 hours. The reaction mixture was filtered, and the filtrate poured into 30 ml. of water, acidified with dilute hydrochloric acid and the precipitate collected. The precipitate was taken up in benzene and chromatographed on silica gel. Elution with 10% ethyl acetate in benzene yielded about 100 mgs. of the title compound.

EXAMPLE 3 Preparation of the compound of formula (13) The indicator dye prepared in Example 1 above (2 equivalents) was dissolved in ethanol (1 gm./ ml.) in a 3-neck round-bottom flask fitted with mechanical stirrer, thermometer, and dropping funnel. n-Dodecylamine (2.5 equivalents) was dissolved in ethanol (1 gm./ ml.) and added in one portion to the reaction vessel. To the wellstirred solution, formalin (containing about 1.5 equivalents formaldehyde) in ethanol (1 ml./ 5 ml.) was added dropwise over 1 hour at a rate such that the temperature of the reaction mixture did not exceed 30 C. and the mixture stirred at room temperature for several hours. The reaction mixture was filtered and washed with ethanol and the ethanol evaporated. The residue was washed with hexane to remove all unconverted dodecylamine.

The amine-substituted intermediate obtained above was dissolved in dry pyridine (1 gm./ 10 ml.) in a flame-dried round-bottom flask fitted with a dropping funnel and chilled in an ice bath to about 5 C. Acetyl chloride (5 equivalents) was added dropwise. When addition was complete, the cooling bath was removed and the reaction mixture allowed to come to room temperature. The reaction mixture was poured into dilute hydrochloric acid. The solid that formed was collected, dissolved in methanol (1 gm./40 ml.) and filtered. Dilute alkali was added, and after stirring for about an hour, the precipitate was collected, washed and dried and recrystallized from ethyl acetate/hexane to yield the title compound.

EXAMPLE 4 Preparation of the compound of formula (12) (a) 3 hydroxy 3 (3' carbomethoxy-4'-hydroxynaphthyl) naphthalide-1.8 (50 gms., 0.125 mole) was suspended in dry benzene (500 ml.) in a flame-dried 1 liter round bottom flask fitted with a magnetic stirrer and calcium sulfate drying tube. Thionyl chloride (16.4 gms., 0.137 mole) was added in one portion followed by 2.5 ml. of dry N,N-dimethylformamide. The suspension was stirred at room temperature for 1 day. The 3-chloro- 3 (3' carbomethoxy-4'-hydroxynaphthyl) naphthalide- 1,8 product was collected on a Biichner funnel and Washed with a small amount of dry hexane. Residual solvent was removed in a vacuum desiccator.

(b) A fresh amount of silver tetrafluoroborate (20.6 gms., 0.106 mole) was Weighed into 900 ml. of dry dioxane. 1 Hydroxy 6 octadecyloxy-Z-naphtholic acid (400 gms., 0.088 mole) was then added to the slurry. The reaction was placed under an atmosphere of nitrogen and with good stirring (55.4 gms., 0.132 mole) of the pseudo chloride prepared in step (a) was added. The mixture was then heated to reflux. A deep purple color began to appear as the reaction proceeded with concomitant precipitation of silver chloride. After 2-3 hours of reflux an additional (3.8 gms., 0.02 mole) of silver tetrafluoroborate was added. Reflux: was continued for an additional 14 hours. Water, 10 ml. was carefully added to the hot mixture and the reaction then cooled to room temperature and filtered through. a 'pad of Celite. The brown filtrate was evaporated to" dryness and the dark residue triturated with ml. of boiling benzene. After cooling the benzene, the solid was filtered. The benzene filtrate was evaporated in vacuo and the gummy residue dissolved in 50-60 ml. of boiling absolute ethanol. After standing for several hours 7.0 g. of product was filtered. The filtrate was evaporated to half volume and allowed to stand overnight to give approximately 2.0 g. of unreacted acid contaminated with a small amount of product. This filtrate was taken to dryness and the residue dissolved in 50-60 ml. of glacial acetic acid. After remaining overnight an additional 8.4 g. of product was obtained. The combined crops were recrystallized from about 200 ml. of glacial acetic acid to give 11.4 gms. of the half-ester product as a grey-white solid (melting range 230-232 (3.

(c) The half-ester (5.5 gms., 6.55 mmole) was dissolved in 250 ml. of warm dioxane and diluted with ml. of ethanol. To the solution was added 250 ml. of 3% potassium hydroxide. The deep blue solution was heated on the steam bath for 2 to 3 hours at which time the color of the reaction mixture was deep green. The solution was cooled to room temperature and acidified With 10% hydrochloric acid while stirring vigorously. A brown gum precipitated which after several hours was sufficiently solidified to be filtered. The solid collected was recrystallized from glacial acetic acid (approximately 1 gm./10O ml.) to give 4.8 gms. of the title compound as a white solid (melting range 263-265 C.).

The 1 hydroxy-6-octadecyloxy-Z-naphthoic acid employed in step (b) above was prepared by adding sodium methoxide (67.4 gms., 1.35 mole) to a solution of 1,6

dihydroxy-naphthalene (100 gms., 0.625 mole) in 900 ml. of dry N,N-dimethyl-formamide saturated with dry carbon dioxide gas. A steady flow of carbon dioxide was maintained throughout the reaction. Approximately 125 ml. of dimethylformamide was distilled and the mixture was then refluxed for 15 minutes and an additional 125 ml. of solvent removed. The solution was cooled and the flow of carbon dioxide stopped. The reaction mixture was acidified with concentrated hydrochloric acid and then poured onto about 2000 gms. of ice. The precipitated dark solid was filtered and dried and then triturated with 1 liter of boiling benzene and filtered free of dark impurities. Recrystallization from water gave 1,6-dihydroxy- 2-naphthoic acid as a white solid (melting range 220- 221 C.).

To a well-stirred slurry of 1,6-dihydroxy-2-naphthoic acid (5.1 gms., 0.025 mole) in 50 ml. of dry isopropyl alcohol under nitrogen was added potassium t-butoxide (5.65 grns., 0.050 mole). The mixture was heated to reflux and stirred 10-15 minutes and then octadecyl bromide (8.35 gms., 0.025 mole) was added. The reaction was refluxed for hours, cooled and acidified with 20% hydrochloric acid. The solid which precipitated was filtered and dried and recrystallized from absolute ethanol to give 3.8 gms. of grey solid. Further recrystallization from chloroform gave 2.3 gms. of 1-hydroxy-6-octadecycloxy- 2-naphthoic acid as a white solid (melting range 164- 165 C.).

EXAMPLE 5 Preparation of the compound of formula (1 l) A mixture of 3-chloro-3-(3'-carbomethoxy-4'-hydroxynaphthyl) naphthalide-1,8 (0.84 gms., 2.0 mmole) Z-(bistrifluoromethyl carbinol)-1-naphthol (0.62 gms., 2.0 mmole) and silver tetrafiuoroborate (0.40 gms., 2.0 mmole) in 75 ml. of dioxane was refluxed for 4 hours. Water (1 ml.) was added to the warm mixture followed by filtration through Celite. The filtrate was evaporated in vacuo and the residual gum dissolved in approximately 25 ml. of hot benzene. On cooling 1.0 gm. of precipitate was collected and recrystallized from a mixture of 2 ml. of chloroform and 25 ml. of benzene to give 0.8 gm. of solid (melting range 260262 C. dec.). The solid obtained (0.5 gm.) was dissolved in ml. of hot ethanol, and the ethanol solution was added to 100 ml. of aqueous potassium hydroxide. The resulting deep blue solution was heated on a steam bath for 2 hours, cooled to room temperature and acidified with hydrochloric acid. After standing for several hours, 0.35 gm. of the title compound was obtained as a white microcrystalline powder (melting point 227 C. dec.).

Indicator dyes containing as the hydrogen-bonding group, a fluoroalkyl carbinol substitutent, form the subject matter of copending US. Patent Application Ser. No. 204,350 of Richard B. Greenwald filed Dec. 2, 1971.

EXAMPLE 6 Preparation of the compound of formula (9) A mixture of 3-chloro-3-(3'-carbomethoxy-4-hydroxynaphthyl) naphthalide (0.42 gm., 0.001 mole), methyl-1- hydroxy-8-naphthoate (0.2 gm., 0.001 mole), and silver tetrafiuoroborate (0.2 gm., 0.001 mole) in 40 ml. of dioxane was refluxed for 5 hours. The solution was filtered through Celite, water added and the resulting solution evaporated to dryness and azeotroped several times with methanol. The residue was dissolved in petroleum etherethanol and cooled. The precipitate formed was collected and then dissolved in 12 ml. of aqueous sodium hydroxide and 36 ml. of ethanol. The solution was heated on a steam bath for minutes, cooled and made acidic with concentrated hydrochloric acid. The ethanol was evaporated and the solid material collected by filtration was taken up in ether. The ether solution was filtered, evaporated to dryness and triturated with petroleum ether.

14 The petroleum ether was evaporated to yield the title compound (melting range 206-2l0 C. dec.).

EXAMPLE 7 Preparation of the compound of formula (10) 3-Hydroxy 3-(3'-carbomethoxy-4'-hydroxynaphthyl) naphthalide-1,8 (2.0 gms.) was suspended in 250 ml. of anhydrous methanol and the suspension saturated with dry hydrogen chloride gas. Most of the solid dissolved to give an amber solution. The solution was refluxed for 30 minutes, cooled and the solvent removed in vacuo. The residue was triturated with ether and filtered. After recrystallization from chloroform-isopropanol, 1.5 gms. of 3 methoxy 3 (3'-carbomethoxy-4'-hydroxynaphthyl) naphthalide was obtained (melting range 232233 C. dec.).

A mixture of 3-methoxy 3 (3'-carbomethoxy-4'-hydroxynaphthyl) naphthalide (1.5 gms.), 6-dodecycloxy-1- naphthol (1.2 gms.) and boron trifluroide-etherate (0.8 gm.) in ml. of benzene was refluxed overnight. The reaction mixture was evaporated to dryness and heated on a steam bath with methanol-petroleum ether. The solid material was collected by filtration, boiled in isopropanol and filtered. The solid was dissolved in tetrahyclrofuran and extracted with 6% aqueous sodium hydroxide (20 ml.). The organic solution was then extracted with 20% hydrochloric acid. Sodium chloride and dichloromethane were added and the solution was dried over magnesium sulfate and evaporated to dryness. The residue was recrystallized from benzene-isopropanol to give the title compound.

EXAMPLE 8 Preparation of the compound of formula (8) A solution of '3-hydroxy-3-(3'-carbomethoxy-4'-hydroxynaphthyl) naphthalide-1,8 (528 mgs.), 2-hexadecyll-naphthol (480 mgs.), and boron trifluoride etherate (184 mgs.) in glacial acetic acid (12 cc.) was refluxed 3 hours. The solution was cooled and evaporated to half-volume. On standing a solid formed which was purified by recrystallization from ethanol.

A solution of 0.8 gms. of the solid obtained above in 25 ml. of ethanol was treated with 5 m1. of 10% sodium hydroxide. After heating the solution on the steam bath for 2 hours, the reaction mixture was cooled and acidified with 20% hydrochloric acid. A gum precipitated and was scratched and triturated with water until solidification was complete. The solid was air dried and then dissolved in boiling cyclohexane. A white solid precipitated from the hot solution almost immediately which was collected to yield 0.5 gm. of the title compound (melting range 214- 215 C.).

EXAMPLE 9 Preparation of the compound of formula (3) 37.6 grams (0.2 mole) of 1-hydroxy-2-naphthoic acid and 20.3 grams (0.2 mole) of 3,3-dichlorophthalide were dissolved in ethyl ether by heating. The resulting solution was cooled and 23 ml. (0.2 mole) of stannic chloride was added dropwise. The mixture was stirred at room temperature for about 48 hours, after which the ethyl ether was removed by evaporation, leaving a green oil. Upon the addition of ethanol, the solution turned pink and a white solid precipitated out. The white solid was removed by filtration and sodium hydroxide was added to the filtrate until it became basic. The base-insoluble material was filtered and the resulting filtrate acidified with acetic acid. A pink solid was obtained, filtered, and then dissolved in aqueous alkali. The base-insoluble material was filtered off and the filtrate was acidified with acetic acid to give a precipitate.

This procedure was repeated until the precipitate obtained upon acidification was a purple solid. The purple solid was placed on a silica gel column and the column eluted with dichloromethane containing 1% methanol which was increased to methanol. At 20% methanol most of the product was removed. The fractions containing prod uct were combined and were evaporated down to yield a total of 350 mg. of material. Recrystallization from 50 ml. of hot 2-methoxyethanol yielded the title compound as a light purple solid (melting range 273 275 0.).

EXAMPLE 10 Preparation of the compound of formula (2) 10 g. (0.049 mole) of the methyl ester of 8-hydroxy-1- naphtholic acid, 2.3 ml. (0.016 mole) phthaloyl chloride and 5.8 ml. (0.05 mole) of stannic chloride were mixed with stirring at 110 C. and reacted for about two hours. The dark brown viscous reaction mixture was poured into ice water without cooling, and the resulting solid was reduced to small particles by grinding and then taken up in a mixture of water and chloroform. The chloroform layer was washed well with water and then dried for chromatography. The material was placed on a Florisilchloroform column. Elution with chloroform removed a few yellow impurities and further elution with chloroform removed the base-soluble product which fraction was suspended in 100 ml. of ethanol under nitrogen. The suspension was treated with 6% aqueous sodium hydroxide (100 ml.) under nitrogen on a steam bath for 30 minutes. The ethanol evaporated ofi during heating to leave a green solution which was cooled in ice and adjusted to a pH 5 with 10% hydrochloric acid. An orange-tan solid precipitated. The solid was filtered and washed with water and dried to give 2.3 g. of material (melting range 165 168 C.). The turbid filtrate was extracted with ethylacetate to give 0.4 g. additional solid which Was combined with the previous solid.

The 2.7 g. of material obtained was then treated with ethanol and the ethanol-insoluble solid discarded. The ethanol solution was evaporated to a goo which was taken up in 5% aqueous sodium bicarbonate. The bicarbonate insoluble material was discarded and the bicarbonate solution acidified with glacial acetic acid. The precipitate formed was filtered, washed with warm water and dried to yield about 0.7 gram of brown solid which was taken up in a 1:4 mixture of methanol and benzene. After standing overnight, a dark brown oil precipitated to leave a light yellow supernatant. The solvent was removed from the supernatant, and the yellow oil remaining was hydrolyzed. A tan solid was obtained which was dissolved in about 3 ml. of glacial acetic acid. After standing for a few minutes, the solution was filtered to collect the title compound as a cream colored solid was was dried at 100 C. (melting range 2l2.-213 0.).

As noted previously, by substituting one and preferably both p-hydroxy-naphthyl radicals with a hydrogen-bonding group in the manner discussed above, the resulting indicator dyes are colored at a higher pH which renders them particularly useful as optical filter agents in photographic processes. For example, l-naphthol phthalein has a lower pKa of 7.0. In comparison, the compounds as represented in formulae (2) and (3) have a pKa of 8.5 and 12.5, respectively. In comparison to l-naphthol naphthalein which has a lower pKa of about 8.5, the compounds as represented in formulae (9), (7) and (12) have apKa of 9.8, 12.8 and 13.9. respectively. (l-naphthol naphthalein was prepared in accordance with the method of Example 9 above by reacting l-naphthol with 3,3-dichloronaphthalide in the presence of stannic chloride.)

Since most commercially useful photographic processes are conducted under alkaline conditions, indicator dyes may be selected from the above-denoted class for use as optical filter agents in photographic processes, e.g., conventional tray processing and diffusion transfer processes where development of a photosensitive material is conducted in the presence of extraneous incident light. The dyes described above have a highly colored, lightabsorbing form in alkaline media at a pH above their respective pKa and a substantially colorless form, i.e., a form which is substantially non-light-absorbing in the visible region in less alkaline media at a pH below their respective pKa. For use in such processes, an indicator dye or dyes may be selected from the aforementioned class of compounds which will be in a colored or lightabsorbing form at the particular pH employed during development and which may be converted to a substantially non-light-absorbing form subsequent to at least the initial stages of development to permit viewing of the final image. In photographic processes where the optical filter agent is retained in association with the final image formed, it may be readily converted to a form which does not interfere with viewing of the image and which does not detract from the brilliance, hues and other properties of the image.

In its preferred embodiment, the present invention provides indicator dyes that are particularly useful in diffusion transfer proecsses and especially in diffusion transfer photographic processes employing composite photosensitive elements such as those described in aforementioned US. Pat. 3,415,644. In such processes, a highly alkaline processing composition having a pH of 13-14 or higher is employed so that it is desirable to use an optical filter agent having a pKa of 11 or preferably 12 or higher that will provide protection from incident actinic radiation during the processing interval but subsequent to the initial stages of development may be rapidly converted to its colorless form to permit early viewing of the final image.

When utilized in diffusion transfer processes employing composite photosensitive elements, the indicator dyes used as the optical filter agents may be initially disposed in a layer of the composite film unit but preferably are initially disposed in the processing composition applied subsequent to selective photoexposure of the photosensitive structure. When incorporated into the processing composition. it is desirable that the dyes selected exhibit good stability in highly alkaline media in addition to broad spectral absorpton in the visible spectrum and a high pKa. Also, the dyes employed as optical filter agents are preferably substantially non-ditfusible in the alkaline processing composition in order to achieve optimum efficiency as a radiation filter and to prevent ditfusion of filter agent into layers of the film unit where its presence mav be undesirable.

Indicator dyes which possess these preferred characteristics are those represented in Formula (II). These indicator dyes possess the desired unique combination of properties, namely. (1) efficient absorption of actinic radiation within the wavelen th range of about 550 nm. to 700 nm.. 2) a high pKa of 11 or more. (3) stability in highly alkaline media, and optionally, (4) non-diffusibility in aqueous alkali. As noted above, the photographic use of these dyes as optical filter agents in photographic processes is disclosed and claimed in copending US. Patent Application Ser. No. 103,392 filed concurrently herewith.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

17 What is claimed is: 1. A compound of the formula:

R1 on on a wherein one of R and R is hydrogen and the other is a hydrogen-bonding group selected from carboxy, hydroxy, o-hydroxyphenyl, sulfonarnido and sulfamoyl; R and R each are selected from hydrogen, alkyl having 1 to 16 carbon atoms and a hydrogen-bonding group selected from carboxy, hydroxy, o-hydroxyphenyl, sulfonamido and sulfamoyl, at least one of R and R being hydrogen; R is selected from hydrogen and alkoxy having 1 to 18 carbon atoms; and X represents the atoms necessary to complete a ring-closing moiety'selected from phthalide and naphthalide, said ring-closing moiety being unsubstituted or substituted with a substituent selected from carboxy and alkoxy having 1 to 16 carbon atoms.

2. A compound as defined in claim 1 wherein X represents phthalide.

3. A compound as defined in claim 1 wherein X represents naphthalide.

4. A compound as defined in claim 1 wherein R is a hydrogen-bonding group and R is hydrogen.

5. A compound as defined in claim 1 wherein R is hydrogen and R is a hydrogen-bonding group.

6. A compound as defined in claim 5 wherein R is carboxy.

7. A compound as defined in claim 4 wherein R is carboxy.

8. A compound of the formula:

wherein R and R the same or difierent, each are hydrogen-bonding groups selected from carboxy, hydroxy, o-hydroxyphenyl, sulfonamido and sulfamoyl, R is selected from hydrogen and alkoxy having 1 to 18 carbon atoms, and X represents the atoms necessary to complete a ring-closing moiety selected from phthalide and naphthalide, said ring-closing moiety being unsubstituted or substituted with a substituent selected from carboxy and alkoxy having 1 to 16 carbon atoms.

9. A compound as defined in claim 8 wherein X represents phthalide.

10. A compound as defined in claim 8 wherein X represents naphthalide.

11. A compound as defined in claim 8 wherein R is carboxy.

12. A compound as defined in claim 11 wherein R is carboxy.

13. A compound as defined in claim 8 wherein R is sulfamoyl.

14. A compound as defined in claim 13 wherein R is sulfamoyl.

15. The compound of the formula:

on coon coon on wherein one of R and R is hydrogen and the other is a group containing a heteroatom possessing an active unshared pair of electrons selected from 0, N and S, said heteroatom possessing a proton more acidic than the proton of the adjacent OH and ionizing to a negative charge in basic solution to form an intramolecular hydrogen bond with said OH, said group forming a 5-, 6- or 7-membered intramolecular hydrogen-bonded ring with said OH; R and R each are selected from hydrogen, alkyl having 1 to 16 carbon atoms and a group containing a heteroatom possessing an active unshared pair of electrons selected from O, N and S, said heteroatom possessing a proton more acidic than the proton of the adjacent OH and ionizing to a negative charge in basic solution to form an intramolecular hydrogen bond with said OH, said group forming a 5-, 6- or 7-membered intramolecular hydrogen-bonded ring with said OH, at least one of R and R being hydrogen; and

20 X represents the atoms necessary to complete a ringclosing moiety selected from phthalide and naphthalide, said ring-closing moiety being unsubstituted or substituted with a substituent selected from carboxy and alkoxy having 1 to 16 carbon atoms. 22. A compound-of the formula: 5'

wherein R and R the same or difierent, each is a group containing a heteroatom possessing an active unshared pair of electrons selected from 0', N and S, said heteroatom possessing a proton more acidic than the proton of OH and ionizing to a negative charge in basic solution to form an intramolecular hydrogen bond with said OH, said group forming a 5-, 6- or 7-membered intramolecular hydrogen-bonded ring with said OH; R is selected from hydrogen and alkoxy having 1 to 18 carbon atoms; and X represents the atoms necessary to complete a ring-closing moiety selected from phthalide and naphthalide, said ring-closing moiety being unsubstituted or substituted with a substituent selected from carboxy and alkoxy having 1 to 16 carbon atoms.

References Cited UNITED STATES PATENTS ,t

2,505,486 4/1950 Green 260343.3 X 2,980,696 4/1961 Korbl zen-343.3 x

JOHN M. FORD, Primary Examiner US. Cl. X.R. 

